Spin Waves in Mixed Magnetic Alloys.
Spinwaves in mixed magnetic alloys are studied by the single-site coherent potential approximation. A theory developed by Roth for the case of diluted alloys is extended to the case where both the components are magnetic making use of the method of Blackman et al. The theory is applied to both ferro- and antiferromagnetic systems. Density of states and spectral functions are calculated using isotropic approximation. For ferromagnetic system the density of states results are calculated for simple, body centered and face centered cubic lattices. These results are compared with the results obtained by Alben et al by computer simulation technique. The results give good agreement except that the single-site approximation does not reproduce the sharp structure below the percolation limit. For antiferromagnetic system density of states are calculated for a realistic square lattice Rb(,2)Mn(,x)Ni(,1-x)F(,4) and the results obtained are compared with the results of Kirkpatrick et al. The result exhibits the qualitative features of the density of states spectrum but the agreement is less good in ferromagnetic case, presumably because the localized effects are not reproduced by the single-site theory.
- Pub Date:
- Physics: Condensed Matter